ksmbd: fix potencial 32bit overflow from data area check in smb2_write

DataOffset and Length validation can be potencial 32bit overflow.
This patch fix it.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/smb2pdu.c

@@ -6197,8 +6197,7 @@ static noinline int smb2_write_pipe(struct ksmbd_work *work)
 	    (offsetof(struct smb2_write_req, Buffer) - 4)) {
 		data_buf = (char *)&req->Buffer[0];
 	} else {
-		if ((le16_to_cpu(req->DataOffset) > get_rfc1002_len(req)) ||
-		    (le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req))) {
+		if ((u64)le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req)) {
 			pr_err("invalid write data offset %u, smb_len %u\n",
 			       le16_to_cpu(req->DataOffset),
 			       get_rfc1002_len(req));
@@ -6356,8 +6355,7 @@ int smb2_write(struct ksmbd_work *work)
 		    (offsetof(struct smb2_write_req, Buffer) - 4)) {
 			data_buf = (char *)&req->Buffer[0];
 		} else {
-			if ((le16_to_cpu(req->DataOffset) > get_rfc1002_len(req)) ||
-			    (le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req))) {
+			if ((u64)le16_to_cpu(req->DataOffset) + length > get_rfc1002_len(req)) {
 				pr_err("invalid write data offset %u, smb_len %u\n",
 				       le16_to_cpu(req->DataOffset),
 				       get_rfc1002_len(req));